xamarin/Xamarin.Forms

[Android] RecycleElement List: using bindings for FormattedText results in "requestLayout() improperly called" issues

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#3,335 opened on Jul 18, 2018

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Description

Description

I have a list with CachingStrategy set to RecycleElement. When using bindings for a label's FormattedText the console is filled with messages like requestLayout() improperly called by {...}.FormsTextView{...} during layout: running second layout pass

Steps to Reproduce

  1. Create a List with CachingStrategy set to RecycleElement
  2. Add simple cells: a label with FormattedText linked to a bindable property in the view model
  3. Fast scroll up and down

Expected Behavior

The list should scroll smoothly with no errors

Actual Behavior

Application Output is filled with messages like the one above. The scroll's behavior doesn't seem to be impacted when the debugger is not connected. These messages are not displayed when binding to a CLR property which creates a new FormattedString() instance on each get or when using RetainElement as a CachingStrategy.

Basic Information

  • Version with issue: Xamarin.Forms 3.1.0.637273
  • Last known good version: ?
  • IDE:
  • Platform Target Frameworks:
    • Android: 8.1
  • Affected Devices: I can name Huawei Nexus 6P (API 27) but it happens on other devices too

Reproduction Link

FormattedTextRepro.zip

Contributor guide

Research direction
Investigate the layout pass in FormsTextView when FormattedText is bound in a recycled list cell. Look for improper calls to requestLayout during layout. Compare behavior between RecycleElement and RetainElement to identify the difference.
Tech stack
csharpandroid
Domain
mobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Xamarin.Forms
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50